Solids conveying system for compacted, friable solids that can not be pushed or compressed

ABSTRACT

A gas conveying system capable of conveying a solid material without pushing or compressing the solid material. The system comprising: at least one conduit assembly comprising a conduit, a lance assembly disposed about a first end of the conduit which is capable of removing the solid material from a holding device, and a first eductor which is capable of entraining the solid material in a gas stream and moving the solid material through the conduit; a cyclone disposed about a second end of the conduit, the cyclone being capable of separating the solid material from the gas stream; and a second eductor disposed to receive the solid material from the cyclone, the second eductor being capable of entraining the solid material in a second gas stream which has a solid-material-to gas mass ratio which is greater than that of the first eductor. The second stage eductor transports the particles further downstream for storage, additional transport, or for further treatment, such as burning in an incinerator.

FIELD OF THE INVENTION

This present invention relates to a system for conveying solidmaterials. More particularly, this invention relates to a conveyingsystem which is capable of transporting compacted, friable solidmaterials, particularly partial oxidation (POX) carbon, without pushingor compressing the solid material.

BACKGROUND OF THE INVENTION

Partial oxidation (POX) carbon requires being transported from a bed ofagglomerated POX carbon particles to a container, incinerator or otherlocation which can be at a higher pressure than the pick-up location.Incineration of the POX carbon requires storage and subsequent transportof the POX carbon to the incinerator. POX carbon is a material withunusual properties. It is a powder which appears dry but consists of 80to 90% free water contained inside a spherical structure of carbon. Thepowder is friable and easily separates when agglomerated particles arepulled apart. However, it behaves like a solid mass when pushed orcompressed.

Because of its physical properties, conventional solid handlingequipment that push or compress handled material cannot be used tohandle POX carbon. Screw conveyors, drag chain conveyors, rotaryfeeders, and the like, have been found to cause the POX carbon tocompress into a solid mass and, therefore, have not been able to providereliable, plug free conveyance of the friable POX carbon material.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a novelrobotic handling and pneumatic conveying system which is capable oftransporting particles of friable, non-free-flowing solid materials,such as POX carbon, using a conveying system that does not push orcompress the solid material during transport. That is, the gas conveyingsystem of the present invention provides accelerating and impact forcesthat are relatively mild compared to other conventional materialhandling technologies.

It is still a further object of the present invention to provide aunique material conveying system wherein no moving parts contact thematerial being transported there-through.

It is also an object of the present invention to provide a unique endeffector (i.e., a robotic-guided vacuum pick-up lance) which comprises acutting disk, vacuum pick-up and mechanical lump breaker. This endeffector is capable of slicing a section of the friable material from acompressed bed thereof, and mechanically breaking or mashing the sliceinto particles that can then be readily transported through the conveyorsystem without causing plugging.

Finally, it is an object of the conveyor system according to the presentinvention to use co-axial eductors which allows the solids material tobe conveyed such that it passes in a straight line through the eductor,thus avoiding the requirement of conventional eductors where the solidmaterial must experience a turn of up to about 90 degrees duringtransporting.

SUMMARY OF THE INVENTION

The present invention is directed to a two-stage air or other gasconveying system for conveying particles of a friable material withoutpushing or compressing the particles into a solid mass. This uniquetwo-stage pneumatic conveying process or system is capable oftransporting POX carbon from a bed of agglomerated POX carbon particlesto a container, incinerator or other location which can be at a higherpressure than the pick-up location. Although especially useful for forconveying particles of friable material, the present two-stage gasconveying system can also be advantageously used to transport otherparticulate matter.

The pneumatic (or other gas) conveying system comprises: at least oneconduit assembly comprising a conduit, a means disposed about a firstend of the conduit which is capable of removing the solid material(e.g., partial oxidation carbon) from a holding means, and a firsteductor which is capable of entraining the solid material in a gasstream and moving the solid material through the conduit; a separatingmeans (i.e., a cyclone) disposed about a second end of the conduit, theseparating means being capable of separating the solid material from thegas stream; and a second eductor disposed to receive the solid materialfrom the separating means, the second eductor being capable ofentraining the solid material in a second gas stream which has a solidmaterial to gas mass ratio which is greater than that of the firsteductor.

The second eductor is preferably capable of transporting the solidmaterial downstream for either storage, treatment or further transport.

It is also preferable to provide an acceleration spool between thecyclone and the second eductor. The acceleration spool is capable ofaccelerating the solid material and gas expelled from the bottom of thecyclone. The cyclone typically includes an inlet and outlet, wherein thecyclone includes a means for preventing the plugging of the inlet.

The first eductor and second eductors preferably produce dischargepressures that are up to about 20.6 KPa above the eductor inletpressure, when the pressure of the motive fluid applied to the eductorsis about 7.9 bar. When a higher pressure motive fluid is used, theeductor discharge pressure will also be higher. The solid material togas mass ratio of the first eductor is between about 0.5:1 to 1.5:1;whereas the solid material to gas mass ratio of the second eductor isbetween about 1:1 to 4:1. The first eductor and second eductor arecompressed air (or gas)-driven coaxial eductors.

The means disposed about a first end of the conduit which is capable ofremoving the solid material from a holding means is preferably a novellance assembly which comprises: a means which is capable of separating aportion of the solid material from a compressed block of the solidmaterial and/or crushing the portion of the solid material intoparticles of a predetermined size which may be transported via theconduit assembly.

Each system preferably comprises a means (i.e., a robotic guide) whichis capable of positioning a lower end of the lance assembly below asurface of the solid material in the holding means and moving the lanceassembly in a predetermined pattern through the holding means.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagrammatic representation of the conveying system of thepresent invention; and

FIG. 2 is a perspective view of a one pick-up head suitable for use withthe conveying system of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As can best be understood with reference to FIG. 1, the presentinvention is directed to a two stage gas conveying system, generallyreferred to by reference numeral 1. The conveying system includes afirst stage eductor 3, in line with a conduit 5. A first end of conduit5 is provided with a pick up head 7, adapted to remove particles of thePOX carbon, or other friable, solid material 10 from a storage orholding bin 9 and entrain the particles in a gas stream.

The solid material entrained in the gas stream are transported throughconduit 5 to cyclone 13, or other similar separating means. The gasstream enters cyclone 13 through cyclone inlet 15. The cyclone 13separates the bulk of the gas from the solid material or particles, anddischarges the separated gas through a backpressure control valve 17.The POX carbon and a small amount of gas are discharged through cycloneoutlet 19. The carbon to gas ratio leaving cyclone 13 is controlled byvarying the setting of backpressure control valve 17. Because gas isremoved in cyclone 13, the solid material to gas mass ratio of the gasstream leaving cyclone 13 will be greater than the solid material to gasmass ratio entering cyclone 13, which provides for more efficienttransport of the particulate or solid material.

Preferably, acceleration spool 21 is provided on cyclone outlet 19.Acceleration spool 21 conveys and accelerates the POX carbon and gasleaving cyclone 13. From acceleration spool 21 the gas stream withentrained particles enters a second stage eductor 23, which dischargesthe POX carbon and gas into the second stage conduit 25. The stagnationpressure at the discharge of the second stage eductor 23 can be, forexample, about 0.123 MPa (3 psig). With POX carbon, a solid to gas massratios of between about 1:1 to 4:1 has been achieved. These ratios arehigher than those obtainable in the first stage (i.e., carbon to gasmass ratios of between about 0.5:1 to 1.5:1) of the conveying system, inwhich a greater mass of gas is needed to effect removal of the materialfrom storage or holding bin 9. From second stage eductor 23, theparticles are transported through second stage conduit 25 to a locationremote from cyclone 13, for further processing or disposal. As anexample of disposal, the POX carbon can be transported to incinerator 27to be burned. Preferably, the particles are ejected from second eductor23 of the conveyor system under positive pressure. Alternatively, theparticles can be transported to at least one additional cyclone (notshown), to provide for additional stages, whereby the solid material canbe transported in the additional stages to a further remote location.

As an alternative to the foregoing, a two stage conveying system can beprovided without the second stage eductor. In such an embodiment, secondstage conduit 25 receives the discharge from cyclone 13 directly, orthrough acceleration spool 21. By omitting second stage eductor 23,cyclone outlet 19 can be provided with a greater diameter. The greaterdiameter cyclone outlet 19 allows the passage of larger particlesthrough the second stage of the conveyor system, and reduces theoccurrence of cyclone plugging. However, operation without second stageeductor 23 requires cyclone 13 to be operated with a higherback-pressure since second stage eductor 23 is not present to pull theparticles from cyclone outlet 19. Higher back pressures force theparticles from cyclone 13, but reduce the inlet velocity of at lanceassembly 31. The inlet velocity at pick-up head 7 dictates the amount ofparticulate pulled into the system from storage or holding bin 9.

The conveying system of the present invention can be operated with alance assembly 31 having a single pick-up head 7, or more preferably,can be provided with a lance assembly 31 which includes multiple pick-upheads, each of which communicates with a separate or individual firststage eductors 3. The eductors, including the first stage eductor oreductors, and the second stage eductor, are preferably coaxial eductors,which are commercially available products known to those of ordinaryskill in the art. Coaxial eductors allow the solids being conveyed topass through the eductor in a straight line, thus avoiding the 90 degreeturn associated with the use of non-coaxial eductors.

The cyclone described above as a separating means useful in the practiceof the present invention is also a conventional piece of equipment knownto those of ordinary skill in the art. When used with multiple pick-upheads, however, the conventional cyclone needs to be modified to havemultiple cyclone inlets. Preferably, the cyclone inlet, or inlets, willbe provided with an anti-fouling baffle 29, the purpose of which is toprevent the accumulation of solids on the wall of the cyclone which cansluff-off and foul the cyclone.

A second aspect of the present invention is a lance assembly 31 that canbe used in combination with the two-stage gas conveyor system describedabove. A preferred embodiment of a suitable lance assembly is shown inFIG. 2 and comprises a pick-up head 7 provided with a central airpassage 33 through which particulate matter entrained in a gas streamcan pass. A first end 35 of pick-up head 7 is attached to a plate 37,formed with beveled edges 39. Beveled edges 39 of plate 37 allow theplate to penetrate compressed blocks of solid material, and slice arelatively thin section therefrom. Each pick-up head 7 of the lanceassembly further comprises one or more pistons 45 that are provided withpiston arms 47 adapted to reciprocate toward and away from plate 37 in adirection parallel to central air passage 33. The ends of piston arms 47are provided with crushing surfaces 49 that in their extended positioncontact, or nearly contact, plate 37.

In operation, lance assembly 31 is moved in a direction substantiallyparallel to the top of a compressed block of a solid friable material,such that beveled edges 39 of plate 37 penetrates the block of thefriable material to slice a relatively thin section therefrom. The sliceof solid, friable material, which rests on top of plate 37, is thencontacted by the reciprocating crushing surface 49, which crushes theslice of solid material between crushing surface 49 and plate 37, toform particles of the solid material. The particles of solid material,under influence of the motive gas stream provided by first stageeductors 3, are then sucked, along with gas, into central air passage33, through side openings 51 provided in pick-up head 7 proximal plate37.

The lance assembly 31 can comprise a single pick-up head 7, orpreferably, can comprise a plurality of pick-up heads, each providedwith associated crushing means. When a plurality of pick-up heads 7 areused, they can be arranged in a single line, in a side by sideconfiguration, or in any other configuration relative to each other.Pick-up heads 7 can be attached to a common plate 37, which can beelongated, or widened to accommodate a plurality of pick-up heads 7 andprovide sufficient area for the crushing surfaces associated therewith.The lance assembly 31 can be manually manipulated through the compressedblock of friable material, or can be controlled automatically by, forexample, robotic means 53, as shown in FIG. 1.

With the foregoing description of the invention, those skilled in theart will appreciate that modifications may be made to the inventionwithout departing from the spirit thereof. Therefore, it is not intendedthat the scope of the invention be limited to the specific embodimentsillustrated and described.

What is claimed is:
 1. A gas conveying system which is capable of conveying a solid material without pushing or compressing said solid material, said system comprising:at least one conduit assembly comprising a conduit, a means disposed about a first end of said conduit which is capable of removing said solid material from a holding means, and a first eductor which is capable of entraining said solid material in a first gas stream, in a first solid-material-to-gas mass ratio, and moving said solid material through said conduit; a separating means disposed about a second end of said conduit, said separating means being capable of separating said solid material from said first gas stream; and receiving means for receiving said solid material from said separating means and entraining said solid material in a second gas stream which has a second solid-material-to-gas mass ratio which is greater than said first solid-material-to-gas mass ratio.
 2. The system of claim 1, wherein said receiving means comprises a second eductor.
 3. The system of claim 2, wherein said second eductor is capable of transporting said solid material downstream of said second eductor.
 4. The system of claim 3, wherein said separating means is a cyclone.
 5. The system of claim 4, further comprising an acceleration spool disposed between said cyclone and said second eductor, wherein said acceleration spool is capable of accelerating said solid material and a residual portion of said first gas stream expelled from a bottom outlet of said cyclone.
 6. The system of claim 4, wherein said cyclone includes an inlet and an outlet, wherein said cyclone further includes a means for preventing plugging of said inlet.
 7. The system of claim 6, wherein said plugging preventing means is an antifouling baffle.
 8. The system of claim 1, wherein said first solid-material-to-gas mass ratio of said first eductor is between about 0.5:1 to 1.5:1.
 9. The system of claim 2, wherein said first solid-material-to-gas mass ratio of said first eductor is between about 0.5:1 to 1.5:1.
 10. The system of claim 9, wherein said second solid-material-to-gas mass ratio of said second eductor is between about 1:1 to 4:1.
 11. The system of claim 1, wherein said means disposed about the first end of said conduit which is capable of removing said solid material from said holding means is a lance assembly which comprises: a means which is capable of separating a portion of said solid material from a compressed block of said solid material and crushing said portion of said solid material into particles of a predetermined size which may be transported via said conduit assembly.
 12. The system of claim 11, further comprising means which is capable of positioning a lower end of said lance assembly below a surface of said solid material in said holding means and moving said lance assembly through said holding means.
 13. The system of claim 1, wherein said first eductor is a compressed gas-driven coaxial eductor.
 14. The system of claim 2, wherein said first eductor and said second eductor are compressed gas-driven coaxial eductors.
 15. The system of claim 1, wherein said solid material is a partial oxidation carbon.
 16. The system of claim 11, wherein multiple said conduit assemblies are disposed between said holding means and said separation means. 